Ferrocene derivatives (compounds and electroconductive polymers containing ferrocene groups) have been used in various applications utilizing electroconductivity. For example, JP 5-103974 A, JP 6-235812 A and JP 7-68156 A disclose methods of using the ferrocene derivatives as surfactants (micelle-forming agents) in electrochemical processes for efficiently producing organic films usable for electronic materials such as color filters.
Further, known applications of redox layers comprising the ferrocene derivatives include an enzyme electrode composition comprising a resin and an electroconductive enzyme prepared by modifying an enzyme with a mediator of a ferrocene derivative (see JP 7-151727 A); an ion-selective electrode using a monolayer membrane comprising a particular ferrocene-containing compound as an intermediate layer between a metal electrode and an ion-sensitive membrane (see JP 8-327584 A); a threading intercalator comprising a particular ferrocene-containing compound, which is combined with an electrochemical analysis device to form a kit for electrochemically detecting DNA fragment samples (see JP 2001-226376 A); etc.
JP 8-245672 A discloses a liquid crystal compound of a particular ferrocene derivative with excellent orientation. Further, JP 2001-85075 A discloses a method of using an electroconductive polymer comprising a cross-linked polymer impregnated with a ferrocene derivative and a solvent in an electrolyte layer of a photoelectric conversion device, thereby providing a photoelectric conversion device higher in photoelectric conversion efficiency than conventional ones.
As described above, the ferrocene derivatives can be used in various applications. In recent years, high-electroconductivity polymers useful for electrochemically controllable gel actuators have been demanded. For example, JP 11-169393 A discloses an artificial muscle, which comprises a formed solid electrolyte and a polyaniline film formed thereon in an insulated state, so that it can be freely deformed in a predetermined direction by the difference of potential applied to the polyaniline film.
Electroconductive ferrocene-containing polymers are mainly those having ferrocene groups connected to polyethylene glycol as described in JP 5-103974 A, JP 6-235812 A and JP 7-68156 A, and those having cross-linked polymers impregnated with ferrocene derivatives as described in JP 2001-85075 A. These electroconductive polymers have limited ferrocene concentration, thereby showing insufficient electroconductivity.
To increase the ferrocene concentrations of the ferrocene-containing electroconductive polymers, the ferrocene derivatives preferably have associability (self-organizing properties), particularly gelling properties. When ferrocene derivatives having the gelling properties are formed into gels or cast films, it is expected that they have increased ferrocene concentration. However, such ferrocene derivatives having gelling properties are not described in the above prior art references.